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LC/LJ Top speed with 2.78 diff ratio.

Started by _J.A.W._ , Jul 25 2014 04:50 PM

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#1 _J.A.W._

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Posted 25 July 2014 - 04:50 PM

I helped my nephew sort out fitting a fairly crisp 186 - solid 30/70 cam, 350 Holley, ported 10-1 head, scorcher dizzy...

into a trimagic LC SL, replacing the tired 161, & we were both fairly impressed by the way the speedo wound way past

its last marker at 120mph.. ..it did start getting a bit light/floaty in the front then though.. ..I can see why they fitted an

air dam under the front on the XU1s.

 

Has anyone on the forum with a really potent XU1 - tried max top end - with a 2.78 or 2.60 diff ratio?


Edited by J.A.W., 25 July 2014 - 04:51 PM.

#2 _sunburst73-xu1_

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Posted 25 July 2014 - 05:10 PM

I'd be interested in where the RPM was at that speed??


#3 N/A-PWR

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Posted 25 July 2014 - 05:14 PM

G'Day James,

 

I too like the 2.78 for up and go, but the LC / LJ Torana wouldn't  survive a 2.78 rev out.

 

Would be something like 7500rpm divided by 2.78:1 = 2697 rotations of the rear wheel per minute.

 

23" O.D. Tyre = 584mm x 3.142 ( Pi ) = 1835mm circumference.

 

2697 x 1835 = 4950539mm per minute ( 4950 metres a minute ).

 

4950 x 60 = 297,000 metres an hour ( 297kph ).

 

 

I thought at 5400rpm with a 3.08:1 diff doing 143mph ( 229kph ) was close to their handling using 5/8 coils and swaybars.

 

also, are you sure your speedo gear was correct for the 2.78,

 

because the 350 Holley and the way past the 120 marker part has me thinking.

 

 

 

 

 

EDIT:-

but yeah, would be nice to see how fast someone has gone ( 160mph )?


Edited by GASPOWER, 25 July 2014 - 05:27 PM.

#4 _sunburst73-xu1_

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Posted 25 July 2014 - 05:28 PM

I spose gearbox and Tyre/rim size would play a part as well.


#5 N/A-PWR

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Posted 25 July 2014 - 05:36 PM

I had 211/60/13 all round, at the time Dane'o


#6 _J.A.W._

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Posted 25 July 2014 - 06:03 PM

No tacho fitted, but it revved out pretty healthily, past the ton in 2nd..

- 2.78 was stock trimagic final drive ratio, had 185/13s on Sunbird 5.5 steels..

 

I had an LJ 173 trimagic/2.78 which I lowered/fitted spoilers sway bars, 195/70 13s on widened 6ín steels

 & an X-2 twin carb/dual exhaust..

 It too would also wind out past the 200kmh final speedo reading,&  felt more planted ( but took longer to do it)..

 

Someone must have a GPS - to run an accurate read out?


Edited by J.A.W., 25 July 2014 - 06:06 PM.

#7 _macdou_

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Posted 25 July 2014 - 06:10 PM

You can download plenty of GPS based speed apps on IPhones and the like. I used one call Speedometer on the iphone, measures 0-100, 1/4 Mile and obviously speed either digital or analogue and MPH or KPH. I used it in my LJ when the speedo was busted..

#8 N/A-PWR

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Posted 25 July 2014 - 06:14 PM

That's great information Ken.


#9 _J.A.W._

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Posted 25 July 2014 - 06:24 PM

Yeah, I have to say I was a bit impressed by that li'l 186, it had been built by a bit of a nutter, he'd been running it in a big fat VH Val coupe, of all things,  & in front of a 5 speed Celica box ..

..it had a forged 179 crank, Starfire rods, hi-po oil pump ( good oil pressure with the solid cam)

 & a trick dirt track inlet manifold/Holley set-up. plus that odd EFI Holden 6-type  3 x 2-1 extractor system.

 

I took him for a decent blast in my 265 Charger, & he saw the light, so we picked up the 186 for a decent price ( not much..)..


Edited by J.A.W., 25 July 2014 - 06:33 PM.

#10 _victor_

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Posted 25 July 2014 - 06:49 PM

2.78 lsd m20 four speed 186/192 9 port xu1 head with plenty more work, starfire rod racing piston roller rockers and wade cam. Don't remember grind Triple 150 cd. 235/50/13

Once you get to around the 160 km mark you speedo needle is jumping all over the place. when it goes past to about 5 mil before 0 it stops still jumps but it like pined there.

The doors start to open and while the powers down, handling is on the right on edge, the scary thing is slowing down. One wrong bump and you dead.

Some we're around 6000 to 6500 rpm.

Not really what your looking at that speed.

One last thing how reliable the taco was ?

Young and dumb.

Victor

#11 _J.A.W._

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Posted 25 July 2014 - 06:59 PM

Hell yeah..

& don't forget to have all the windows wound up tight , or the bloody headliner will pop down - to see what its all about - too..


#12 _Lazarus_

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Posted 26 July 2014 - 12:05 AM

speedtrials2002-016.jpg

 

Year Vehicle Class MPH Record 2001 72 LJ Holden Torana E/PRO 113.392 121.64 2002 72 LJ Holden Torana E/PRO 133.729 133.48 2003 72 LJ Holden Torana E/PRO 143.856 136.798 2004 72 LJ Holden Torana E/PRO 145.560 155.844 2005 72 LJ Holden Torana D/GC 121.114 Open 2006 72 LJ Holden Torana D/GC 159.101 195.047 2009 72 LJ Holden Torana D/GC 132.782 195.047 2010 72 LJ Holden Torana D/GC 164.308 195.047 2011 72 LJ Holden Torana D/GC Washed Out 195.047 2012 72 LJ Holden Torana D/GC Washed Out 195.047 2013 72 LJ Holden Torana D/GC 103.830 195.047
 

 

 

http://www.dlra.org....rofiles/250.htm


#13 N/A-PWR

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Posted 26 July 2014 - 01:07 AM

Tarmac is better


#14 _J.A.W._

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Posted 26 July 2014 - 08:42 AM

Thanks Laz,  & 164mph, not too shabby, even if ~30mph short of the record..

& I'd reckon maybe the LC nose is a bit more aero-dynamic - as stock - though.


#15 N/A-PWR

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Posted 26 July 2014 - 10:09 AM

Hi LAZ,

 

The Torana was Yellow for the 164mph Land-speed Record Racing, and did it have a 2.78 diff, don't think so,

 

as the length of the Strip required a quick pick-up for 4.5miles,

 

maintain the Top Speed for 1mile, and slow down for 4.5miles.

 

and go 2% faster in the opposite direction, which both times average is the Recording.

 

 

The Motor was either a 2926cyl or a V8 in which the V8 Supercars use a 3.15 diff for Bathurst and still do 185mph.

 

 

Brocky did 167mph with a 3.08 diff.


#16 MustardGTR

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Posted 26 July 2014 - 12:40 PM

To me it looks like the 72 LJ Holden SL Torana  managed 145.560 mph in the E/PRO category. Still very impressive for a 202. It would be interesting to know what carburetor(s) it run. (i.e. Torana SL = standard 1bbl?).  


#17 N/A-PWR

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Posted 26 July 2014 - 12:47 PM

I used a 500 Holley for 143mph.

 

It would be interesting to know what carburetor(s) it run.


#18 _J.A.W._

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Posted 26 July 2014 - 12:58 PM

Looks like that LJ is still running a six, but a bigger one from Chev..

 

http://www.dlra.org.au/2014-03.htm


Edited by J.A.W., 26 July 2014 - 01:00 PM.

#19 _Lazarus_

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Posted 26 July 2014 - 03:29 PM

Dave both Supercars and Brock's A9X used oversized tyres so the ratios are not really applicable without taking that into consideration.

 

Most of the salt lake cars are so overgeared they need a push vehicle to take off.

 

As for factory speedos, In my days of youthful stupidity I've done 120mph on a long straight road in Sydney in a 307 HK and 90mph in a 1300 Beetle on the old Princess Hwy south of Sydney for a couple of examples. Were those speeds correct ? I seriously doubt it, especially the VW lol.

 

I have also ridden a skateboard down Conrod Straight before they bent it to slow everyone down a bit. It is hard to imagine a better length of tarmac for clocking a high speed. I'm sorry but I find it impossible to believe that you have really done 143mph in an LJ on a public road. 


#20 _J.A.W._

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Posted 26 July 2014 - 03:50 PM

Ask Larry Perkins about his doing just that ( or faster) in the HDT 308 LJ mule on test..


#21 N/A-PWR

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Posted 26 July 2014 - 04:10 PM

Ha Ha Mark,

 

Yep took till the next town for the Cop to catch up, and I got fined 100 bucks for doing it.

 

 

BTW - I did it between Singleton and Muswellbrook N.S.W. on the way to Scone. and I left all the Cars around me behind in 1983.

 

 

 

 

So yeah, the RAT will have a LSD 2.78 Diff and will Test it on a Track some Time in the Future.


Edited by GASPOWER, 26 July 2014 - 04:20 PM.

#22 _J.A.W._

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Posted 26 July 2014 - 04:17 PM

Oh no Gas-P, you sucker - you  got busted, should've made a run for it..

 

& what a bad boy, you'd get locked up for that theses days..


#23 N/A-PWR

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Posted 26 July 2014 - 04:25 PM

You are not wrong James,

 

Us Torana Guy's at the Time were alway's looking for Speed, like the Kooragang Island Industrial Area, Heron Rd in Newcastle.

 

Oh no Gas-P, you sucker - you  got busted, should've made a run for it..

 

& what a bad boy, you'd get locked up for that theses days..


#24 gtrboyy

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Posted 26 July 2014 - 05:54 PM

Beat me to to it! As fast as the rooflining lets you go haha

 

They get hell floaty at high speed front end feels so light that a decent gust of wind will blow you into next lane.

 

Memories of winding car off the clock crossing moonee moonee bridge...


#25 N/A-PWR

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Posted 26 July 2014 - 06:06 PM

he he,

 

remember when they put the road between the 1st moonbi mountains nsw coming towards Newcastle,

 

I would throw the Torana in neutral, and would coast up to 100mph from 60mph,

 

that was good, better than going around all those bends of the old descent.

 

Beat me to to it! As fast as the rooflining lets you go haha

 

They get hell floaty at high speed front end feels so light that a decent gust of wind will blow you into next lane.

 

Memories of winding car off the clock crossing moonee moonee bridge...



straight down it was, and about 3 km's long?


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